BR Gen Chem question - density and solute

[harkkam]

I dont understand the explanation they have given me in the back.

Given that a solute is denser than the solvent into which it dissolves, what is TRUE of the concentration measurements of different solutions made up solely of the two components?

A. The solution with the greatest density also has the greatest molarity and molality.

B. The solution with the greatest density also has the greatest molarity but the molality is the same for all solutions.

C. The solution with the greatest density also has the lowest molarity and molality.

D. The solution with the greatest density also has the lowest molarity, but the molality is the same for all of the solutions.


The answer is A.

No idea how to solve this one.

Im confused on how density relates to all the other concepts of molarity and molality.

I know density = mass of solution/volume of solution

but dont see how I could take that and understand what it would do to the molarity and molality

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[IntelInside]

I dont understand the explanation they have given me in the back.

Given that a solute is denser than the solvent into which it dissolves, what is TRUE of the concentration measurements of different solutions made up solely of the two components?

A. The solution with the greatest density also has the greatest molarity and molality.

B. The solution with the greatest density also has the greatest molarity but the molality is the same for all solutions.

C. The solution with the greatest density also has the lowest molarity and molality.

D. The solution with the greatest density also has the lowest molarity, but the molality is the same for all of the solutions.


The answer is A.

No idea how to solve this one.

Im confused on how density relates to all the other concepts of molarity and molality.

I know density = mass of solution/volume of solution

but dont see how I could take that and understand what it would do to the molarity and molality

Molarity is moles of solute/liters of solution
Molality is moles of solute/kg of solvent


Now what about molarity and molailty? If I add solvent to 10 ml of solute with a higher density, I will have more grams per ml of solute than I would from a lower density liquid. Therefore since I have more grams I will have more moles therefore molarity/molality increases

 

[harkkam]

Now if the solute is denser than the solvent it is going to reduce the kg of solvent more than if the solute was less dense than the solvent.


and If I add solvent to 10 ml of solute with a higher density, I will have more grams per ml of solute than I would from a lower density liquid

Thats whats making it hard for me to understand, I dont get that.

What does solute density have to do with solvent kg.

I thought that no matter how dense the solute is the amount of Kg of solvent will remain the same.

If I put a steel block inside a jar of water. There are still the same amount of kg's of water as before.

If I put a plastic block which is less dense inside a jar of water. There are still the same amount of kg's of water as before.

I dont see how solute density will change that

 

[jpatel]

Since solute is more dense, more solute you add to solution more dense is the solution going to be.

Thus, higher density solution would contain more solute = higher molality and molarity


Simple as cake

 

[Morsetlis]

Thats whats making it hard for me to understand, I dont get that.

What does solute density have to do with solvent kg.

I thought that no matter how dense the solute is the amount of Kg of solvent will remain the same.

If I put a steel block inside a jar of water. There are still the same amount of kg's of water as before.

If I put a plastic block which is less dense inside a jar of water. There are still the same amount of kg's of water as before.

I dont see how solute density will change that

Molarity and molality in this case talk about the entire solution's molarity and molality. Sure, if you drop a steel block into a jar of water, the water won't change much--but now your "solution" also comprises the mass and volume taken up by the steel block.

Look:

Given that a solute is denser than the solvent into which it dissolves, what is TRUE of the concentration measurements of different solutions made up solely of the two components?